No abstract

Glass bars and plates were subjected to impact loading. Failure waves were observed to propagate behind the compression waves. Material traversed by the failure wave suffers total loss of tensile strength and substantial drop in shear strength. Failure wave propagation velocities exceed the maximum crack propagation speed, but are not constant. In bars, failure wave speed range from 2.3 to 5.2 mm/μs, increasing with increasing impact velocity; in plates, the wave speed is about 2 mm/μs. The failure is ‘‘explosive’’ in nature, leading to radial expansion in bars and an increase in mean stress in plates.

No abstract

No abstract

High-velocity impact onto a layered glass target produces a very extensive damage pattern exhibiting many distinct morphologies. Material around the penetration cavity is finely comminuted. Under the arrested projectile, the glass is largely intact with spokelike fracture regions. Around the projectile cavity, needle fragments are formed; they are radial in outer layers and circumferential in inner layers. Extensive radial cracks occur in all layers, but the spacing and frequency of transverse fractures change in each layer. Damage from radial cracks also progresses from being hoop-stress-induced to flexural-induced through the depth of the target. Fan and dicing cracks occur near the periphery of the target. Mesoscale damage features include conventional mist and hackle markings indicating very fast cracks. The map of damage presented herein should be a valuable reference for attempts to model impact damage of glass.

No abstract

No abstract

Une série d'expériences d'impacts de plaques sur des verres sodo-calciques et pyrex a été réalisée, pour étudier les ondes de rupture, récemment mises en évidence par Kancel et al II/. L'existence de ces ondes est déduite d'observation de figures d'interaction d'ondes et de mesures de contrainte d'écaillage de verres sodo-calciques et pyrex, à l'avant et à l'arrière de ces fronts d'onde. Les verres sodo-calciques et pyrex ont des comportements très différents dans le domaine élastique de compression par choc.